Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in JAVA):

Solution:
import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.Queue;
import java.util.Scanner;

public class Main {

    char[][] field;
    boolean[][] visited;
    int[] dx = {-1, 0, 1, 0};
    int[] dy = {0, 1, 0, -1};
    Queue<Integer[]> q = new ArrayDeque<>();

    void run() {
        Scanner sc = new Scanner(System.in);
        int h = sc.nextInt();
        int w = sc.nextInt();
        field = new char[h][w];
        visited = new boolean[h][w];
        int bCount = 0;

        for (int i = 0; i < h; i++) {
            char[] chars = sc.next().toCharArray();
            for (int j = 0; j < w; j++) {
                field[i][j] = chars[j];
                if (chars[j] == '#') bCount++;
            }
        }
        q.add(new Integer[]{0, 0, 0});
        visited[0][0] = true;

        int count = -1;
        while (!q.isEmpty()) {
            Integer[] next = q.remove();
            int x = next[0];
            int y = next[1];
            int depth = next[2];
            if (x == h - 1 && y == w - 1) {
                count = depth;
                break;
            }
            for (int i = 0; i < 4; i++) {
                int nx = x + dx[i];
                int ny = y + dy[i];
                if (0 <= nx && nx < h && 0 <= ny && ny < w && !visited[nx][ny] && field[nx][ny] != '#') {
                    visited[nx][ny] = true;
                    q.add(new Integer[]{nx, ny, depth + 1});
                }
            }
        }

        System.out.println(count == -1 ? -1 : h * w - 1 - bCount - count);


    }

    void debug(Object... os) {
        System.err.println(Arrays.deepToString(os));
    }

    public static void main(String[] args) {
        new Main().run();
    }

}